NPL's commercial services are built on 100 years of leadership in accuracy, innovation and scientific research. Experienced consultants and project managers draw upon a unique combination of industry know-how and world-leading scientific discovery to deliver real-world business solutions and enable innovation and secure competitive advantage.

We strive to actively promote public awareness and appreciation of science and technology, particularly the importance of measurement and the role of NPL. Here you can find out more about the interesting things we do, science outreach activities you can get involved in or take a look at some of our educational resources.

Why does my radio-controlled clock receive the MSF signal less well at night? (FAQ - Time)

The 60 kHz frequency used by the MSF service was chosen so that users within about 1000 km of the transmitter receive predominantly the ‘ground wave’ signal, which follows the Earth's surface and so has a highly stable path. However, there is also a residual ‘sky wave’ which is reflected off the ionosphere. The ‘sky wave’ component is stronger in winter than summer, and much stronger at night than during daytime. It combines vectorially with the ‘ground wave’ component, and can result in a total received signal that is either stronger or weaker depending on a range of factors including distance from the transmitter, time of day, time of year, and the level of solar activity. The net effect is that the signal strength received during daytime should remain fairly stable, but at night it may vary significantly and give either better or worse reception than usual.